LONDON (Reuters) - Russian Twitter accounts pumped out messages in support of the opposition Labour party in an attempt to influence last year's British election, according to new research.

The research by Swansea University and The Sunday Times found about 6,500 automated accounts sent messages praising the opposition Labour leader Jeremy Corbyn and his policies in the closing stages of the election.

They also attacked Prime Minister Theresa May for refusing to take part in televised election debates and criticized her for cutting police numbers in the wake of the Manchester bombing.

The study found nine out of 10 messages from the accounts about Labour backed the party. In contrast, nine out of 10 tweets about the Conservatives were hostile.

"These new revelations are extremely concerning," the culture minister Matt Hancock said in a statement. "It is absolutely unacceptable for any nation to attempt to interfere in the democratic elections of another country."

The British government has accused Russia of meddling in elections around the world and planting fake stories in the media, but has denied Russia has successfully interfered in British elections.